1. Field of the Invention
The present invention relates to a novel plant which belongs to the genus Limonium and has a characteristic of undergoing flower bud differentiation without encountering low temperatures.
2. Description of the Background
Limonium plants, which are generally called statice, are ornamental plants used as cut flowers or the like. These plants have a characteristic that they do not form flower buds unless encountering low temperatures. Thus, generally, these plants are seeded in fall to meet with low temperatures in winter. Plants seeded in fall will flower around April to May in the next year.
In order to induce their flowering at an earlier stage (sometime from December to March), an artificial low temperature treatment must be given. At present, forcing culture of Limonium plants to achieve early flowering is carried out as described below.
In case of seedling propagation, seeds are sown in seeding boxes around August. One day after the seeding, when the seeds have absorbed moisture and become active, they are placed in a refrigerator at 2-4.degree. C. for 30-40 days to induce flower bud differentiation with low temperature stimulation. Around September, the refrigerated seedlings are taken out of the refrigerator and raised in pots. Then, they are transplanted in a greenhouse in soil beds. When the temperature considerably drops around November, the inside of the greenhouse is heated to thereby promote flow stalk development and flowering.
In case of vegetative reproduction using herbaceous cuttings, mericlones or the like, axillary buds or apical meristems are collected from the plants with flower buds already differentiated. The seedlings resulting therefrom are grown under low temperature conditions. Then, they are planted in a greenhouse in fall. Thereafter, they are cultivated in the same manner as in seedling propagation.
Although the above-mentioned methods make it possible to induce the flowering of Limonium plants at an early stage, there have the following problems.
First, investment to facilities such as refrigerators to provide low temperatures is required.
Secondly, since seedlings are kept under darkness in a refrigerator (which is different from their natural growing conditions) for a long period, a large number of plant bodies are withered when they are taken out of the refrigerator.
Further, if the plants taken out of the refrigerator meet with high temperatures, flower stalk development will not occur due to devernalization. They will not flower unless they are vernalized again by low temperatures. In order to avoid devernalization, seeding time is chosen so as for the seedlings to be taken out of the refrigerator in the fall when the temperature is cool enough, or seedlings must be raised in the air-conditioned room until there is no danger of devernalization (i.e., the temperature is sufficiently low). In addition, when the seedlings raised in the air-conditioned room are planted in a greenhouse, the temperature of the greenhouse must be sufficiently low to prevent devernalization. Thus, flowering time can be advanced only to a certain extent, which is dependent on the temperature of the place of cultivation).